1. Field of the Invention
This invention relates to a vehicle seat device and more particularly to a lock device of a seat back for a vehicle seat assembly.
2. Prior Art
As prior art, a lock device for a seat back is disclosed in a Japanese Utility Model Application situ-kai-sho 63(1988)-47948 published in 1988. This prior art discloses a seat back lock device for a vehicle seat assembly having a latch mechanism engaging with or disengaging from a striker secured on the vehicle body, an operating element for causing the latch mechanism to be disengaged from the striker, and a cancelling mechanism disposed between the latch mechanism and the operating element for permitting or preventing the transmission of the latch-disengagement force from the operating element to the latch mechanism.
According to this prior art, the cancelling mechanism includes a cancelling lever for the cancelling operation, a first rotation lever engaged with the operating element, a second rotation lever engaged with the latch mechanism, and a lock pin. The lock pin is inserted into the cancelling lever, the first and second rotation levers and engages with, or disengages from, the first and second rotation levers.
According to the structure of the prior art, the cancelling lever is operated to move the lock pin relative to the first and second rotation levers. This movement of the lock pin engages or disengages the first and second rotation levers to permit or prevent a transmission of the latch-disengagement force from the operation element to the latch mechanism.
The lock pin has to be associated with the three levers (cancel lever, first lever and second lever) by being inserted into the three levers. It is therefore necessary for this structure to have at least three levers and one lock pin and other components to assemble or operatively fix these parts.
Accordingly, it is an object of the present invention to provide an improved seat back lock device for a vehicle seat. It is another object of the present invention to provide an improved seat back lock device which is compact in structure and has fewer components.
According to the present invention, the seat back lock device includes a cancelling lever for operating a cancelling mechanism, a rotational lever operatively connected to an operating element, and a connecting rod engageably inserted into the rotational lever. One end of the connecting rod being connected to a latch mechanism and the other end being connected to the cancelling lever.
Thus constructed present invention has the following advantages. By moving the connecting rod relative to the rotational lever by operating the cancelling lever, a drive connection between the connecting rod and the rotational lever can be selectively created or released, to permit or prevent the transmission of the operating force from the operating element to the latch mechanism. Accordingly, the second rotational lever used in the prior art mentioned above can be eliminated by an arrangement wherein the connecting rod performs the functions of both the second rotational lever and the connecting rod of the prior art, thereby reducing the number of components.
It is another aspect of the present invention to provide an L-shaped elongated hole in the rotational lever for inserting the connecting rod thereinto.
It is still another aspect of the present invention to provide a base bracket mounted on the latch mechanism for rotatably supporting the rotational lever.
It is a further object of the invention to provide a seat back lock device including the connecting rod movably disposed between the rotational lever and the base bracket.
It is still another object of the present invention to provide the cancelling lever slidably supported on the base bracket.
Another aspect of the invention is to provide a seat back lock device having a supporting portion formed on the rotational lever to support the cancelling lever in cooperation with the base bracket.
Preferably the seat back lock device of the present invention includes the cancelling lever integrally formed with the operating element to be operated by an occupant of the seat and held in either connected position or released position by a turn over spring.